In usual sealing systems of this kind having an O-ring 32 as a sealing element, the sealing element is seated in a radial outer groove 26 of the valve housing 22 whereby the end of the valve housing to be connected to the fuel rail 10 is formed by a groove limiting flange 23 which abuts a ring surface 18 at the bottom 16 of a circular cylindrical rail branch 12 incorporating the valve housing 22, and which borders the bore 11 of the rail 10 at the branch-off point (see FIG. 8).
The disadvantage of such a sealing system is that the sealing elements used in low-temperature conditions must have special material properties to suit this application, yet they fail at temperatures below minus 40.degree. C. when the swelling of the O-ring caused by the fuel is no longer sufficient to avoid leakage of the sealing element radially outside; please refer to G. Streit and M. Achenbach: "Functionality of elastomer seals at low temperatures by the example of O-rings, part 2: Influence of fuels on the sealing performance at low temperatures", in "Kautschuk, Gummi, Kunststoffe KGK, Internationale Fachzeitschrift fur polymere Werkstoffe" ("Caoutchouc, Rubber, Synthetic Material KGK, International Technical Journal for Polymeric Material"), 10/93 (October 1993, 46th year) p. 812 ff.